Physical Therapy Assistant Practice Exam 2026 - Free PTA Practice Questions and Study Guide

A pressure ulcer that cannot be staged due to the presence of slough or eschar covering the base is classified as unstageable. This classification is used when the full depth of the ulcer cannot be assessed because necrotic tissue obscures the wound bed.

In detail, slough consists of moist, devitalized tissue that appears yellow or white, while eschar is dry, necrotic tissue that can be black, brown, or tan. The inability to see the base of the ulcer prevents healthcare providers from determining the stage based on the depth and extent of tissue damage. By designating a pressure ulcer as unstageable, clinicians can emphasize the need for further assessment and appropriate treatment until the wound can be properly evaluated.

In contrast, stages I, II, and III are defined by specific characteristics related to skin integrity and tissue damage that could be assessed if the wound base were visible. However, when the base is obscured by slough or eschar, these classifications do not apply, leading to the unstageable designation.